Overhead high voltage power transmission or distribution systems typically have a plurality of electrically conductive cables. Spacer clamp arms are used to reduce the possibility of the conductive cables contacting one another, the generation of corona discharge, and the creation of electrical stress and interference. The spacer clamp arm has an elongated arm portion and a cable keeper end portion at one end of the arm. A spacer clamp arm grips a respective conductive cable at the keeper end portion. The other end of the spacer clamp arm is attached to a frame which may have one or more additional spacer clamp arms attached. The spacer clamp arms permit a limited amount of movement of the spacer clamp arms with respect to the frame, and also provide a controlled electrically semi-conductive path between the spacer clamp and the frame, both of which are usually made of metal.
The keeper end portion defines an opening through which a conductive cable passes. The keeper end portion has a hinge structure that can pivot between an open and closed position. In the open position, the keeper end portion of the spacer clamp arm receives the conductive cable. The spacer clamp arm is then clamped shut. A molded rubber clamp liner is placed between the conductive cable and the keeper end portion of the spacer clamp arm.
The known clamp liner is typically rated for use up to 120 degrees centigrade of continuous conductive cable temperature. With the advent of composite core conductors and increased demand for electrical power, conductive cable temperatures often exceed the limit of the known clamp liner. Silicone rubbers can withstand the relatively high surface temperatures but have poor electrical semi-conductive properties. Thus, a need exists for an improved clamp liner capable of withstanding relatively higher conductor temperatures with good electrical semi-conductive properties at a reasonable cost.